A typical example of the dispensers for dispensing the materials described above is a syringe. Such dispensers are known in various other fields such as cosmetics, writing instruments, and the like.
Various dispensing methods of the contents are also known. As one of the methods of classification, they can be divided into the group which advances a male screw member on the basis of force or rotation and the group which does not use a screw. In accordance with the former, the male screw member is meshed with a female screw member formed in a predetermined length and is rotated so as to advance the male screw member. The present invention relates to the former, while an ordinary syringe is an example of the latter.
In comparison with the latter, the former which advances the male screw member on the basis of force of rotation is more advantageous in that the quantity of the content which is dispensed can be controlled and stabilized more easily. However, the structure often gets complicated, and this results in difficulty of assembly. Assembly of a really satisfactory dispenser is not so easy. If the assembly cannot regulate the advance of the male screw member, for example, unnecessary discharge of the content will develop when the dispenser is out of use. Extrusion of the content by the male screw member cannot be effected smoothly unless its movement in the axial direction is controlled. Therefore, the assembly must take this factor into consideration, too.